.TH std::lcm 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::lcm \- std::lcm

.SH Synopsis
   Defined in header <numeric>
   template< class M, class N >                         \fI(since C++17)\fP
   constexpr std::common_type_t<M, N> lcm( M m, N n );

   Computes the least common multiple of the integers m and n.

   If either M or N is not an integer type, or if either is (possibly cv-qualified)
   bool, the program is ill-formed.

   The behavior is undefined if |m|, |n|, or the least common multiple of |m| and |n|
   is not representable as a value of type std::common_type_t<M, N>.

.SH Parameters

   m, n - integer values

.SH Return value

   If either m or n is zero, returns zero. Otherwise, returns the least common multiple
   of |m| and |n|.

.SH Exceptions

   Throws no exceptions.

.SH Notes

   Feature-test macro  Value    Std        Feature
   __cpp_lib_gcd_lcm  201606L \fI(C++17)\fP std::gcd, std::lcm

.SH Example


// Run this code

 #include <iostream>
 #include <numeric>

 #define OUT(...) std::cout << #__VA_ARGS__ << " = " << __VA_ARGS__ << '\\n'

 constexpr auto lcm(auto x, auto... xs)
 {
     return ((x = std::lcm(x, xs)), ...);
 }

 int main()
 {
     constexpr int p{2 * 2 * 3};
     constexpr int q{2 * 3 * 3};
     static_assert(2 * 2 * 3 * 3 == std::lcm(p, q));
     static_assert(225 == std::lcm(45, 75));

     static_assert(std::lcm( 6,  10) == 30);
     static_assert(std::lcm( 6, -10) == 30);
     static_assert(std::lcm(-6, -10) == 30);

     static_assert(std::lcm( 24, 0) == 0);
     static_assert(std::lcm(-24, 0) == 0);

     OUT(lcm(2 * 3, 3 * 4, 4 * 5));
     OUT(lcm(2 * 3 * 4, 3 * 4 * 5, 4 * 5 * 6));
     OUT(lcm(2 * 3 * 4, 3 * 4 * 5, 4 * 5 * 6, 5 * 6 * 7));
 }

.SH Output:

 lcm(2 * 3, 3 * 4, 4 * 5) = 60
 lcm(2 * 3 * 4, 3 * 4 * 5, 4 * 5 * 6) = 120
 lcm(2 * 3 * 4, 3 * 4 * 5, 4 * 5 * 6, 5 * 6 * 7) = 840

.SH See also

   gcd     computes the greatest common divisor of two integers
   \fI(C++17)\fP \fI(function template)\fP
